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package java.sql;

import java.io.Reader;

/**
 * The mapping in the Java&trade; programming language
 * for the SQL <code>CLOB</code> type.
 * An SQL <code>CLOB</code> is a built-in type
 * that stores a Character Large Object as a column value in a row of
 * a database table.
 * By default drivers implement a <code>Clob</code> object using an SQL
 * <code>locator(CLOB)</code>, which means that a <code>Clob</code> object
 * contains a logical pointer to the SQL <code>CLOB</code> data rather than
 * the data itself. A <code>Clob</code> object is valid for the duration
 * of the transaction in which it was created.
 * <P>The <code>Clob</code> interface provides methods for getting the
 * length of an SQL <code>CLOB</code> (Character Large Object) value,
 * for materializing a <code>CLOB</code> value on the client, and for
 * searching for a substring or <code>CLOB</code> object within a
 * <code>CLOB</code> value.
 * Methods in the interfaces {@link ResultSet},
 * {@link CallableStatement}, and {@link PreparedStatement}, such as
 * <code>getClob</code> and <code>setClob</code> allow a programmer to
 * access an SQL <code>CLOB</code> value.  In addition, this interface
 * has methods for updating a <code>CLOB</code> value.
 * <p>
 * All methods on the <code>Clob</code> interface must be fully implemented if the
 * JDBC driver supports the data type.
 *
 * @since 1.2
 */

public interface Clob {

  /**
   * Retrieves the number of characters
   * in the <code>CLOB</code> value
   * designated by this <code>Clob</code> object.
   *
   * @return length of the <code>CLOB</code> in characters
   * @throws SQLException if there is an error accessing the length of the <code>CLOB</code> value
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  long length() throws SQLException;

  /**
   * Retrieves a copy of the specified substring
   * in the <code>CLOB</code> value
   * designated by this <code>Clob</code> object.
   * The substring begins at position
   * <code>pos</code> and has up to <code>length</code> consecutive
   * characters.
   *
   * @param pos the first character of the substring to be extracted. The first character is at
   * position 1.
   * @param length the number of consecutive characters to be copied; the value for length must be 0
   * or greater
   * @return a <code>String</code> that is the specified substring in the <code>CLOB</code> value
   * designated by this <code>Clob</code> object
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value; if pos is less
   * than 1 or length is less than 0
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  String getSubString(long pos, int length) throws SQLException;

  /**
   * Retrieves the <code>CLOB</code> value designated by this <code>Clob</code>
   * object as a <code>java.io.Reader</code> object (or as a stream of
   * characters).
   *
   * @return a <code>java.io.Reader</code> object containing the <code>CLOB</code> data
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @see #setCharacterStream
   * @since 1.2
   */
  java.io.Reader getCharacterStream() throws SQLException;

  /**
   * Retrieves the <code>CLOB</code> value designated by this <code>Clob</code>
   * object as an ascii stream.
   *
   * @return a <code>java.io.InputStream</code> object containing the <code>CLOB</code> data
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @see #setAsciiStream
   * @since 1.2
   */
  java.io.InputStream getAsciiStream() throws SQLException;

  /**
   * Retrieves the character position at which the specified substring
   * <code>searchstr</code> appears in the SQL <code>CLOB</code> value
   * represented by this <code>Clob</code> object.  The search
   * begins at position <code>start</code>.
   *
   * @param searchstr the substring for which to search
   * @param start the position at which to begin searching; the first position is 1
   * @return the position at which the substring appears or -1 if it is not present; the first
   * position is 1
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if pos is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  long position(String searchstr, long start) throws SQLException;

  /**
   * Retrieves the character position at which the specified
   * <code>Clob</code> object <code>searchstr</code> appears in this
   * <code>Clob</code> object.  The search begins at position
   * <code>start</code>.
   *
   * @param searchstr the <code>Clob</code> object for which to search
   * @param start the position at which to begin searching; the first position is 1
   * @return the position at which the <code>Clob</code> object appears or -1 if it is not present;
   * the first position is 1
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if start is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.2
   */
  long position(Clob searchstr, long start) throws SQLException;

  //---------------------------- jdbc 3.0 -----------------------------------

  /**
   * Writes the given Java <code>String</code> to the <code>CLOB</code>
   * value that this <code>Clob</code> object designates at the position
   * <code>pos</code>. The string will overwrite the existing characters
   * in the <code>Clob</code> object starting at the position
   * <code>pos</code>.  If the end of the <code>Clob</code> value is reached
   * while writing the given string, then the length of the <code>Clob</code>
   * value will be increased to accommodate the extra characters.
   * <p>
   * <b>Note:</b> If the value specified for <code>pos</code>
   * is greater then the length+1 of the <code>CLOB</code> value then the
   * behavior is undefined. Some JDBC drivers may throw a
   * <code>SQLException</code> while other drivers may support this
   * operation.
   *
   * @param pos the position at which to start writing to the <code>CLOB</code> value that this
   * <code>Clob</code> object represents; The first position is 1
   * @param str the string to be written to the <code>CLOB</code> value that this <code>Clob</code>
   * designates
   * @return the number of characters written
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if pos is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.4
   */
  int setString(long pos, String str) throws SQLException;

  /**
   * Writes <code>len</code> characters of <code>str</code>, starting
   * at character <code>offset</code>, to the <code>CLOB</code> value
   * that this <code>Clob</code> represents.  The string will overwrite the existing characters
   * in the <code>Clob</code> object starting at the position
   * <code>pos</code>.  If the end of the <code>Clob</code> value is reached
   * while writing the given string, then the length of the <code>Clob</code>
   * value will be increased to accommodate the extra characters.
   * <p>
   * <b>Note:</b> If the value specified for <code>pos</code>
   * is greater then the length+1 of the <code>CLOB</code> value then the
   * behavior is undefined. Some JDBC drivers may throw a
   * <code>SQLException</code> while other drivers may support this
   * operation.
   *
   * @param pos the position at which to start writing to this <code>CLOB</code> object; The first
   * position  is 1
   * @param str the string to be written to the <code>CLOB</code> value that this <code>Clob</code>
   * object represents
   * @param offset the offset into <code>str</code> to start reading the characters to be written
   * @param len the number of characters to be written
   * @return the number of characters written
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if pos is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.4
   */
  int setString(long pos, String str, int offset, int len) throws SQLException;

  /**
   * Retrieves a stream to be used to write Ascii characters to the
   * <code>CLOB</code> value that this <code>Clob</code> object represents,
   * starting at position <code>pos</code>.  Characters written to the stream
   * will overwrite the existing characters
   * in the <code>Clob</code> object starting at the position
   * <code>pos</code>.  If the end of the <code>Clob</code> value is reached
   * while writing characters to the stream, then the length of the <code>Clob</code>
   * value will be increased to accommodate the extra characters.
   * <p>
   * <b>Note:</b> If the value specified for <code>pos</code>
   * is greater then the length+1 of the <code>CLOB</code> value then the
   * behavior is undefined. Some JDBC drivers may throw a
   * <code>SQLException</code> while other drivers may support this
   * operation.
   *
   * @param pos the position at which to start writing to this <code>CLOB</code> object; The first
   * position is 1
   * @return the stream to which ASCII encoded characters can be written
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if pos is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @see #getAsciiStream
   * @since 1.4
   */
  java.io.OutputStream setAsciiStream(long pos) throws SQLException;

  /**
   * Retrieves a stream to be used to write a stream of Unicode characters
   * to the <code>CLOB</code> value that this <code>Clob</code> object
   * represents, at position <code>pos</code>. Characters written to the stream
   * will overwrite the existing characters
   * in the <code>Clob</code> object starting at the position
   * <code>pos</code>.  If the end of the <code>Clob</code> value is reached
   * while writing characters to the stream, then the length of the <code>Clob</code>
   * value will be increased to accommodate the extra characters.
   * <p>
   * <b>Note:</b> If the value specified for <code>pos</code>
   * is greater then the length+1 of the <code>CLOB</code> value then the
   * behavior is undefined. Some JDBC drivers may throw a
   * <code>SQLException</code> while other drivers may support this
   * operation.
   *
   * @param pos the position at which to start writing to the <code>CLOB</code> value; The first
   * position is 1
   * @return a stream to which Unicode encoded characters can be written
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if pos is
   * less than 1
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @see #getCharacterStream
   * @since 1.4
   */
  java.io.Writer setCharacterStream(long pos) throws SQLException;

  /**
   * Truncates the <code>CLOB</code> value that this <code>Clob</code>
   * designates to have a length of <code>len</code>
   * characters.
   * <p>
   * <b>Note:</b> If the value specified for <code>pos</code>
   * is greater then the length+1 of the <code>CLOB</code> value then the
   * behavior is undefined. Some JDBC drivers may throw a
   * <code>SQLException</code> while other drivers may support this
   * operation.
   *
   * @param len the length, in characters, to which the <code>CLOB</code> value should be truncated
   * @throws SQLException if there is an error accessing the <code>CLOB</code> value or if len is
   * less than 0
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.4
   */
  void truncate(long len) throws SQLException;

  /**
   * This method frees the <code>Clob</code> object and releases the resources the resources
   * that it holds.  The object is invalid once the <code>free</code> method
   * is called.
   * <p>
   * After <code>free</code> has been called, any attempt to invoke a
   * method other than <code>free</code> will result in a <code>SQLException</code>
   * being thrown.  If <code>free</code> is called multiple times, the subsequent
   * calls to <code>free</code> are treated as a no-op.
   * <p>
   *
   * @throws SQLException if an error occurs releasing the Clob's resources
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  void free() throws SQLException;

  /**
   * Returns a <code>Reader</code> object that contains a partial <code>Clob</code> value, starting
   * with the character specified by pos, which is length characters in length.
   *
   * @param pos the offset to the first character of the partial value to be retrieved.  The first
   * character in the Clob is at position 1.
   * @param length the length in characters of the partial value to be retrieved.
   * @return <code>Reader</code> through which the partial <code>Clob</code> value can be read.
   * @throws SQLException if pos is less than 1 or if pos is greater than the number of characters
   * in the <code>Clob</code> or if pos + length is greater than the number of characters in the
   * <code>Clob</code>
   * @throws SQLFeatureNotSupportedException if the JDBC driver does not support this method
   * @since 1.6
   */
  Reader getCharacterStream(long pos, long length) throws SQLException;

}
